Finishing textile fabric



y 7, 1963 c. w. SINGLETON 3,382,086

FINISHING TEXTILE FABRIC Filed Sept. 3, 1964 R f ATTORNEYS United States Patent 3,382,08 FINISHING TEXTILE FABRIC Chesley W. Singleton, Altavista, Va., assignor to Klopman Mills, Inc., Asheboro, NC, a corporation of Delaware Filed Sept. 3, 1964, Ser. No. 394,234 4 Claims. (Cl. 117-335) ABSTRACT OF THE DISCLOSURE There is provided a process for producing a permanent white finish on bleached cotton and polyester containing fabrics which finish is not removed by repeated launderings. The fabric is treated with a composition containing at least one resinous thermosetting amino-formaldehyde condensate binder, optical brightening agent and pigment. The fabric is then predried at about 240 F. to 280 F. and thereafter the drying is completed at about 280 F. to 310 F. on an enclosed tenter frame, after which the fabric is cured at about 300 F. to 320 F. by passing over a plurality of heated rolls with the minimum tension necessary to pass the fabric over the rolls.

The present invention relates to a novel process for treating fabric containing cotton, especially cotton/polyester fabric. More particularly, the invention is concerned with the production of permanent white on cotton and cotton/ polyester fabrics, e.g. fabric Woven with blends of cotton and polymeric linear polyesters such as polyethylene terephthalate or the like.

Considerable effort has been expended in the past to obtain a satisfactory White finish on cotton/ polyester fabrics. Normally, white cotton/polyester cloth is prepared by bleaching (e.g. a peroxide bleach) but the resulting product is not as white as desired. Hence, bluing and/or optical brightening agents are used to improve the White color. Thus, for example, it has been proposed in the past to treat cotton/polyester fabric With optical brightener after bleaching the fabric and it has also been suggested that such fabric, e.g. in rope form, might be treated with optical brightener during the bleaching operation itself. The thus treated fabric may then be finished by the application thereto of an appropriate resin followed by curing. Acid colors or pigments for bluing purposes might be added to the resin formulation. Curing is usually accomplished in an oven at uniform heat and in some cases a flash cure at elevated temperatures, e.g. 380-400 F., is utilized.

The prior proposals for obtaining a white finish on cotton/polyester fabric have been unsatisfactory for various reasons. Most importantly, the previous finishes have not been able to withstand repeated laundering and there is a marked tendency for the treated fabric to turn grayish in color or even yellow after only a relatively few washings. This is particularly true when the fabric is exposed to conventional chlorine-containing household bleaches.

Another problem with prior art techniques is that they are not adapted for continuous operation. This is a very serious disadvantage since batch operations in the textile field are necessarily time-consuming and uneconomical.

In my copending application Ser. No. 300,452 filed Aug. 7, 1963, now abandoned, there is described a process which is free from the prior art disadvantages noted above and makes it possible to obtain a permanent white finish on cotton fabric, particularly cotton/polyester fabric. The process described in said application involves continuously treating the fabric with a finishing composition containing at least one resinous binder, optical brightening agent and pigment, and then drying and curing on an en- 3,382,086 Patented May 7, 1968 closed frame, using graduated heat extending over a range of about 340-400 F. This process gives a desirable White finish on cotton/ polyester fabric or the like which remains even after laundering under the: most rigid washing conditions using conventional home detergents and chlorine-containing bleaches.

The principal object of the present invention is to provide certain unique modifications and improvements in the process of Ser. No. 300,452, whereby an even better white finish and other advantages are achieved. Other objects will also be hereinafter apparent.

Broadly stated, the present process involves treating the cotton/polyester fabric, after it has been bleached, with an aqueous composition containing at least one thermosetting resin binder, at least one optical Whitening or brightening agent for both the cotton and polyester and one or more appropriate bluing pigments, drying the fabric on an enclosed tenter frame and then roller curing the fabric at a relatively low, essentially constant temperature, e.g. 300-320 F. The thus cured fabric may then be fed directly into the conventional type of sanforizing operation Without the need for backwashing, solvent treatment or the like, thus making it possible to go from the bleaching operation through the finishing treatment to the sanforizing operation in a continuous series of steps.

As will be appreciated from the above, the present process replaces the flash curing operation of Ser. No. 300,452 (i.e. drying and curing at graduated temperature on the tenter frame) with drying on the frame followed by curing on a roller cure. Additionally, the drying and curing temperatures used herein are substantially lower than those disclosed in Ser. No. 300,452. Thus, for example, the drying temperature used in the present process will usually be in the range of 280-310 F. while curing is carried out at 300-320 F. for 1-3 minutes. A cloth speed of the order of 60-90 yards per minute may be used in practicing the invention continuously.

The invention is illustrated by the accompanying flow sheet wherein the numeral 2 represents a conventional cotton/ polyester fabric, for example, one suitable for use as a shirting material or the like comprising a plain weave or Warp and filling yarns made up of a fiber blend of 65% Dacron polyethylene terephthalate and 35% cotton. Before treatment according to the invention, the fabric 2 is preferably heat set and enzyme desized, and then bleached in conventional manner, e.g. by means of peroxide bleach in a J-boX. After drying, the bleached fabric 2 is padded at 4 with aqueous finishing material of the type described in detail hereinafter. From this operation, where the wet pickup may amount to from 35 to 60% by weight, the fabric is partially dried by passage over two or more dry cans 6 at a temperature of from 240 to 280 F. Normally, this pre-drying operation eliminates from 5 to 20% by Weight of the water picked up from the padding operation.

From the drying cans 6, the fabric is dried on an enclosed tenter frame, broadly shown at 8. The frame holds the fabric out to its finished width and, as indicated, the temperature within the enclosure is kept substantially constant and will usually fall in the range of 2803 10 F., the drying temperature selected for any specific situation depending on the fabric composition and construction, rate of fabric speed, etc.

The time involved for drying on the enclosed frame can be varied depending on the temperature and other operating conditions but usually will fall. in the range of 10 to 60 seconds.

The frame used herein is of conventional construction with the usual means for holding the fabric at the desired width. The frame may be enclosed in any appropriate fashion, e.g. an elongated, suitably insulated housing or oven-like member open only at the ends for passage of 3 the fabric therethrough and provided with a source of dry heat such as hot air, electric elements or the like to effect the desired drying.

After drying on the frame, the fabric is cured in a heated zone by drawing the fabric around a series of rolls 12 using just sufiicient tension to draw the fabric through the zone. During curing, the edges of the fabric are free, i.e. they are not clipped as in the case of the drying operation on the tenter frame. This permits the fabric to shrink uniformly and become stabilized on the rolls while avoiding the possibility of scalloped edges caused by shrinkage between the edge clips of the tenter. Rolls 12 may comprise conventional steel rolls or the like which are free to rotate as the fabric is drawn through the heated zone. The latter may be heated in any convenient fashion, e.'g. hot air, electric elements or through the rolls themselves as may be desired, at a temperature above the drying temperature and in the range of 300-320 F. (e.g. 310 F.) for a period of time between 1 and 3 minutes (preferably 1.5 to 2.5 minutes).

The cured fabric leaving zone 10 may be cooled, if desired, to room temperature by any suitable means, e.g. cooling rolls 14, and may be fed, either with or without such cooling, to conventional sanforizing operations or the like, as may be desired. As indicated heretofore, one of the advantages of the present process is that there is no necessity for either backwashing the cured fabric or washing with solvent, as would generally be the case, before going into some other treatment such as sanforizing.

As in the case of Ser. No. 300,452, the aqueous finishing composition used herein includes the following essential components:

(1) One or more amino-formaldehyde condensates as the thermosetting resin binder with a catalyst for curing the same;

(2) One or more optical brightening agents; and

(3) One or more bluing pigment colors.

In addition, the composition will generally include one or more conventional auxiliary components such as wetting agents, softeners and/ or lubricants to improve hand, softness and other fabric characteristics. Typical auxiliaries contemplated herein include polyethylenes such as Moropol 700, a nonionic polyethylene emulsion useful as a lubricant; starch products or the like including the water-soluble starch ether known as Solvitose HDF used to improve hand and Softset Q, a cationic softener.

The chemical nature of the resin binder, brightening agent and pigment utilized herein may be varied. Thus, conventional water-soluble and readily dispersible thermosetting amino-formaldehyde condensates, including modified or unmodified urea-, melamineand triazine-formaldehydes may be used. Modified ethylene-urea formaldehyde condensates may be specifically mentioned as useful. The resin selected should be capable of crosslinking or otherwise reacting with the cotton component of the fabric and should be chlorine resistant and free from the tendency to pick up chlorine. Usually, the composition used herein will include from about 2 to 6% by weight of resin binder, based on the dry weight of fabric, although it will, of course, be realized that the actual amount used in any specific case will depend on other operating conditions.

Any catalyst conventionally used for curing formaldehyde resins may be used in the present invention. This includes such catalysts as magnesium chloride, zinc nitrate, amine hydrochloride or mixtures thereof. One such catalyst is available as Catalyst 43 which may be chemically described as buffered zinc nitrate. Generally speaking from to by weight of catalyst is used, based on the weight of formaldehyde condensate.

A variety of optical brightening agents (also called fluorescent brighteners or optical bleaching agents) are known for use with polyesters and any of these may be used herein. Agents of this type are described in US. Patents 2,873,206, 2,875,089 and 2,986,528. The brighten- 4 ing agents shown in these patents are free from watersolubilizing groups and contain at least one heterocyclic ring, e.g. an oxazole or imidazole ring, condensed with a benzene ring. Preferred agents described therein are the u:B-di[benzoxazolyl-(2)]-ethylene compounds and the a:fi-di[benzimidazyl-(2)]-ethylene compounds. Other brightening agents include styrylbenzene and stilbene derivatives (US. Patents 3,076,020 and 3,051,704, respectively) and oxdiazoles (US, Patent 2,856,311). The water-insoluble nonionic product known as Uvitex ERN (Ciba) is especially effective for this purpose. This product, which apparently reacts with the polyester, is available in the form of a finely dispersed mobile paste and is described in the abovementioned US. Patent 2,875,089. It may be chemically defined as an azfl-difibenzoaxazolyl- (2) ]-ethylene, notably one where each of the benzoxazolyl radicals carries an alkyl substituent, e.g. methyl in the 5- position.

In addition to using at least one polyester brightener, it has also been found advantageous according to the invention to include one or more cotton brighteners in the finishing composition. Any conventional cotton brightener may be used including those known as Tinopal BFTA, Tinopal GSA, Uvitex CF or Artic White CC (Hilton Davis).

Usually, the amount of brightener used will be in the range of A to A by Weight (for each brightener), based on the weight of the fabric being treated, although proportions outside this range may also be used to advantage.

The pigment or pigments utilized should be selected to give the cotton/polyester fabric the desired tint. These include the well known bluish copper phthalocyanine pigments and the like. Pigments of the Lumatex type have been found especially suitable, particularly a combination of Lumatex Brilliant Violet R (Color index #60005) and Lumatex Blue B (Color index #RBZO). Another suitable pigment of this type is Interchem Pigment Padding Fuchsia N, a quinacridone type pigment.

Usually from .0002 to .0008% by weight of pigment based on the weight of the fabric will give the desired result. Where a mixture of pigments is used, as in the case of Lumatex Brilliant Violet R and Lumatex Blue B, the ratio of the components can be widely varied, e.g. 1:3 to 3:1. Proportions outside this range may also be used depending on the tint desired.

The invention is illustrated with reference to the accompanying drawing by means of the following examples wherein parts and percentages are on a weight basis unless otherwise stated:

Example I Shirt cloth (120 x 72) comprising a blend of 65% Dacron polyester and 35% cotton in both warp and filling, after bleaching in rope form with a conventional peroxide bleach and drying, was padded as shown at 4 with a composition having the following makeup:

Parts in pounds Permafresh Resin 197 20 Catalyst 43 4 Uvitex ERN 4 Lumatex Blue R .03 Lumatex Brilliant Violet R .03

Softset Q 7 Solvitose HDF 2 Moropol 700 12 Water to make 50 gallons Balance The cloth was padded with the above composition at F. to give about a 50% pickup after padding. The

cloth was then partially pre-dried (15% moisture removal) as shown at 6 using a temperature of about 270 F. Generally in this operation, the moisture removal will fall in the range of 5 to 20% of the total water content and temperatures of the order of 240 to 280 F. are used.

After this pre-drying operation, the fabric was dried on the enclosed frame 8 using a drying temperature of 280 F. and a drying time of about 20 seconds. The thus dried fabric was then roller cured and stabilized by drawing the same through zone 10 at 310 F., in 2.5 minutes. The fabric was run continuously through the pad, predry and drying and curing stages at the rate of 90 yards per minute.

The finished product demonstrated a highly satisfactory white color which remained essentially unchanged even after home launderings using detergent and bleach. In contrast, comparative fabrics bleached and processed in conventional manner took on a yellow or grayish appearance even after only five home launderings.

The components of the finishing composition referred to by trade name in the above example may be chemically identified as follows:

Permafresh 197 is a dimethylol cyclic nitrogen compound;

Catalyst 43 is buffered zinc nitrate;

Uvitex ERN has the meaning indicated above;

Lurnatex Blue B is phthalocyanine Blue, dispersed in a resin system;

Lumatex Brilliant Violet R is a vat of the vat violet 9 class dispersed in a resin system;

Softset Q is a quaternary compound;

Solvitose HDF is a water-soluble starch ether;

Moropol 700 is a nonionic polyethylene emulsion.

Example II Example I was repeated except that .1 part of a conventional cotton brightening agent, e.g. Tinopal BFTA, was included in the finishing composition. The resulting product demonstrated an even better white finish and other advantages.

While certain specific operating conditions have been described in the above examples, it will be appreciated that various modifications may be made therein without deviating from the invention. For example, the padding temperature may vary from 70 to 110 F. Variations may also be made in the finishing composition depending on the finish desired, etc.

It will be appreciated that any of the conventional polyester textiles may be used herein as exemplified in Whinfield U.S. 2,465,319 and including, but not limited to, commercial products such as Dacron, Fortrel, Kodel, Vycron, Terylene and the like.

Chemically, the cotton brightening agents referred to above by tradename may be described as follows:

Tinopal BFTA Stilbene-triazine-sulfobenzene-ethanolamine-condensate Tinopal GSA Unsymmetrical-amino-stilbene-triazolenaphthalene-sulfonic-acid-condensate Uvitex CF Fluorescent Brightener 134.

The foregoing description is given only for the purpose of illustration and is not intended to limit the invention as defined in the following claims wherein:

I claim:

1. The process for providing a permanent white finish on bleached cotton and polyester containing fabric which finish is not removed by repeated laundering comprising treating said fabric with a finishing composition containing at least one thermosetting amino-formaldehyde condensate resinous binder, optical brightening agent and pigment, pre-drying the fabric at about 240 to 280 F., then drying said fabric at about 2803 10 F. on an enclosed frame and curing the fabric at about 300 F. to 320 F. by passing the fabric over a plurality of heated rolls with the minimum tension necessary to pass the fabric over the rolls.

2. The process of claim 1 wherein said fabric is also stabilized during curing.

3. The process of claim 1 wherein the fabric is dried in 10-60 seconds and cured in 1-3 minutes.

4. The process of claim 3 wherein said finishing composition includes a polyester brightener and a cotton brightener.

References Cited UNITED STATES PATENTS 2,121,006 6/1938 Bener 117-7 2,338,983 1/ 1944 Thackston et a1 117-7 X 2,424,284 7/ 1947 Olpin et al. 117-145 2,474,909 7/1949 Olpin et al 117-143 X 2,779,684 1/1957 Alles 117-7 2,865,783 12/ 1958 Henderson et a1 117-7 2,945,033 7/ 1960 Hansermann 117-33.5 2,961,349 11/1960 Bartl et a1. 17-138.8 3,018,287 1/1962 Fleck 117-33.5 3,030,224 4/ 1962 Liggett 117-33.5 3,052,570 9/1962 Polansky et al 117-139.4 3,152,132 10/1964 Clarke 117-33.5 3,285,770 11/1966 Hegemann et a1. 117-139.4 X 2,565,358 8/1951 Douglas et a1 117-143 X 2,873,206 2/ 1959 Geigy et al. 117-3.5

WILLIAM D. MARTIN, Primary Examiner. T. DAVIS, Assistant Examiner. 

